GRAND CANYON NATIONAL PARK -- The Grand Canyon’s beauty beckons like gravity, pulling even the timid to the chasm’s edge.

But for those committing to the challenge of a cross-canyon hike, there awaits below the rim a reward beyond the spectacular scenery: time travel.

Those horizontal stripes on the postcard panoramas trace a billion years of geological history. They are the sediment and fossils of ancient oceans. Scott Thybony, who literally wrote the books on canyon trails, says to hike the canyon is to go back an average of 100,000 years with each downward step. As the trail winds and sometimes plummets through layers of hermit shale, redwall limestone and Tapeats sandstone, the canyon deepens and the climate warms. The hiker sheds his outer layers, and even some layers within, when the cell signal is gone, the world is quiet and the mind centers on the simple: food, water and the next footstep.

“There’s something special about being in the canyon,” said Mark Wunner, supervisor at the park’s Backcountry Information Center. “I get excited just thinking about it.”

Our party of four wanted just that kind of primal peace, and we were willing to burn a lot of cash and fossil fuel in the pursuit. We planned our trip for early October of last year on the historic North and South Bass Trails, which start at the north and south rims and meet at the Colorado River. But we wanted to cross the 18-mile-wide canyon without having to backtrack to a car. “The point,” explained fellow hiker Byron Moffett, “is to see all the trails without having to repeat them.”

The solution was to break into pairs in different vehicles, each driving an SUV to a trail head. The North Bass party (Kevin Horan and me) and the South Bass party (Moffett and Scott Mcneil) would hike down, meet at the river, exchange car keys and hike up the other side to the vehicle left by the other party. Simple.

Except for one thing. How does one cross a fast-moving, cold river?

“The safe way is to hitchhike,” Wunner advised. “You wait for a ride (from rafters), and jump up and down when you see somebody coming. It’s not something that’s written about in the guide books.” OK, we thought. We’ll try that.

The Bass Trails are steep, difficult and suitable only for experienced backpackers. “You’re in a real inhospitable place that can hurt you,” Moffett said. “You really have to be aware and have some map skills.”

There are no trail markers, except at the trail heads. And those border on rude: “Do not expect to be rescued,” they warn.

But the Bass Trails are worth the trouble. Built in the late 19th century by their namesake, prospector and tour guide William Bass, the trails are far removed from the more populated corridor routes. That, and a strict permit system, ensure what Wunner calls a “high-quality visitor’s experience.”

The North Bass Trail is longer and steeper but more verdant and with more accessible water. A two-day side trip to the Powell Plateau, an “island plateau” forest of high-country ponderosa pines, brings more adventurous backpackers to Dutton Point, with canyon views to test the acrophobic. Five thousand feet below is the archaeological site at Shinumo Camp, where artifacts remain from old man Bass’ time along the clear and frigid Shinumo Creek. It’s where our hiking parties met for the key exchange, a mere ritual because we carried duplicates, but it was a good excuse to break out the whiskey. Earlier, the south party pals had been ferried across the river by rafters after only a four-hour wait.

Two days later our north party crossed with gracious Grand Canyon Association rafters.

The drier South Bass Trail offered overnight side trips onto terraces of different elevations and environments. Below the Redwall cliffs, the Tonto Trail leads east above the river through vast gardens of low desert scrub to Serpentine Canyon, with 2-inch thorns threatening your ankles with each step. Camping under a full moon, we were visited by a bighorn sheep.

The entire hike could be done in five or six days, but our trip of nine days made the pace easier and allowed for those side trips. As Moffett said, “It takes thousands of years for something to happen there, so you have to slow down and appreciate it.”